CO2 Solubility Characteristics of Crude Oils related to Carbon Capture and Utilization (CCU)

Carbon Capture and Storage (CCS) or Utilization (CCU) are expected to be powerful tools to reduce CO2 emissions to the atmosphere from large scale sources, such as electric power, oil refinery, steal making, cement plants, with continuing their activities Those contain the CO2 separation or capture from flue gases at the plants and the transport and injecting CO2 into oil and gas reservoirs, and coal seams. Those technical operations have been accumulated in petroleum industry. Recently, CCU has been popular rapidly, since it can cover economic investments and operation costs by producing variable fuels (Verland der Chemishen Industries, 2009). It has been applied to fossil fuel productions using CO2, such as Enhanced Oil and Gas Recovery (CO2-EOR and EGR), Enhanced Coal Bed Methane (CO2-ECBM). The cold oil productions by injecting CO2 into oil reservoirs have been investigated. When the oil is produced with injecting captured CO2, the produced oil is expected to be 70% “Carbon-free”, because it can be evaluated from difference between the carbon content in the incremental oil produced and volume of CO2 left in the reservoir. A next generation CO2 storage technology can produce 100% “Carbon-free” oil (Phares, 2008). When injecting CO2 or CH4 into oil reservoirs, the oil swelling coefficient and gas diffusion coefficient in the oil phase are important parameters to carry numerical simulation of cold oil production. The interfacial tension and swelling are usually measured in parallel, and used to evaluate the diffusion coefficient. Dissolution of soluble gas contributes to cold oil production, as it reduces oil viscosity and capillary pressure. It also causes swelling of the oil, which increases oil saturation in reservoir pore space and subsequently the relative permeability of the oil. Measurements of gas diffusion and dissolution behavior in crude oils are required, since gas dissolution is expected to make increase of oil mobility in reservoirs. These oil mobility changes can be used for cold production by understanding drainage mechanisms. The Laboratory of Mineral Resources Production and Safety Engineering, Kyushu University (REPS) has been measured basic CO2 characteristics in oil, coal, rocks and coal reservoirs. In this review, measurement results of CO2 solubility and swelling factor in oils have been presented in order to propose EOR operations by foaming CO2 micro bubbles in the oil.